If there is a natural axial length of the eye, but the eye is not myopic after the optometry examination, there is only one reason for this situation: the refractive power of the lens is larger, the anterior and posterior diameters of the lens are longer, and the refractive power of the eye can still be maintained in the normal range after the generation eliminates part of the axial length of the eye. According to the refractive component, myopia can be divided into two types: First, refractive myopia, which is mainly due to the excessive curvature of the cornea or lens, the refractive power of the eye will exceed the normal range, but the axis length of the eye is still normal. Second, axial myopia, which refers to the case where the refractive power of the eye is abnormal due to the growth of the eye axis later, but the curvature of the cornea and lens are in the normal range, both of which must be problematic for the eye to be abnormal, leading to myopia.